Project 1 ABSTRACT Our long-term goal is to ameliorate the debilitating consequences of age-related hearing loss (ARHL; presbycusis) that are known to impact nearly 70% percent of Americans over the age of 70. ARHL interferes with effective communication by reducing the audibility of sounds, and degrading the intelligibility of speech in quiet and noisy backgrounds. The overall objective of this research is to identify and understand effective methods for modulating ARHL. The central hypothesis of this is that targeted therapeutic interventions will induce plasticity within the peripheral and central auditory system, altering the function of complex gain mechanisms, leading to amelioration of chronic deficits that define presbycusis. This pioneering research uses innovative catalysts to induce functional changes in the aging auditory system. We will leverage cross-project comparative methods to identify the perceptual, neurophysiological, and molecular bases of the resulting peripheral and central auditory plasticity. Aim 1 focuses on the potential to use hormone (aldosterone) supplementation to improve peripheral and central auditory function. Aims 2 and 3 test a series of hypotheses that establish the nature and magnitude of neural plasticity in older adults induced by augmented acoustic environments (AAE). Targeted ARHL deficits include loudness growth, temporal processing, and speech in noise processing. A combination of behavioral and electrophysiological measures and a combination of longitudinal and cross-sectional designs will serve as the basis for the broader comparative research of this proposal. The comprehensive framework proposed here is the first to our knowledge combining basic and applied methods to address central auditory plasticity and the amelioration of AHRL in a manner that allows rapid translation of findings to clinical practice ? the foremost goal of NIA and NIH at large.